Method and apparatus for determining the character and points of ingress of well fluids



Q" 8 4 2m 2 A R. E T C m s mw cw m F ,HTM GmE .RIW ENF m0 S LMS IEM GDm .R RN I .JSO ws. AT RN AI PO PP A D N .A 1 Mm ,M 5 l 1W u J 4 `,Sheets-Sheet 1 Filed Jan. 4, 1939 fmwwwmw H u. Ml il M.m 5 M m M wm M WN doH July' l5, 1941- J. R. GILLBERGH l 2.248,982 4ME'IIOD AND APPARATUS`FOR DETERMINING THE CHARACTER AND POINTS OF INGRE'SS4 OF WELL FLUIDS Filed' Jan. 4, 1939 4 Sheets-Sheet 2 f A rTo/QNE M5 July 15,1941.

(2.248.982 AND v J. R. GILLBERGH SFO METHOD AND APPARATU R DETERMINING THE CHARACTER PoIN'rs oF INGREss oF WELL FLUIns Filed Jan. 4, 1939 4- Sheets-Sheet 3 CURL/f C A B E E V V R R U W C CUR VE D C UR VE E TIME /V MINUTES A U C CUR ve CUV'E CURVE 0 VE F J, ,/nm mw@ m Nm a M R ...f WM H F O ,hv s C4 m W K M Y Y m A a cb E wm E m w. M L M w m ,M m W w UK C C C `C C IO l2 I4 flME /N M/NUTEJ VE CLOSED A r romy/sra 2.248,9382 Anp Y July 15, 1941. J. ILLBERGH METHODJAND APPARATUS FOR DETERMINING THE.i CHRACIER POINTS 0F 'INGRESS OF WELL FLUIDS led Jan.. 4, l1-9 4 Sheets-Sheet 4v HAR/e):

FOR THE F/M Patented July l5, 1941 UNITED STATES `Plirllizil'rA OFFICE METHOD AND APPARATUS FOR DETERMIN- ING THE CHARACTER AND POINTS OF IN- GRESS F WELL FLUIDS Jahn R. Gillbergh, Pasadena, Calif. Application January' 4,1999, serial No. ,249,266v

`27 claims.

My invention relates to the art of exploring deep well bores and is particularly directed to the problem of locating the various levels of fluid ingress. While the principles involved maybe practiced in various methods and apparatus for various purposes, the invention will, it is believed, be most Widely applied to the location o f water intrusion in oil wells. Since outstanding advantages appear`in this latter application vof the invention, I elect to direct my disclosure'specilcally to the problem of exploring an oil well to ascertain sources of water encroachment, no limitation being implied by my election.

Waterintrusion in an oil well tends to increase progressively as production is continued and may threaten not only to flood the well, but also to spread over and ruin a whole oil ileld by migrating from one stratum to another. Such intrusion is almost always restricted tostrata of lngress so limited in vertical extent that only relatively simple local remedies are necessary to .protect the well. Accurately ascertaining the levels of water ingress, however, more often than not is extremely difficult. Both a high degree of skill and extensive experience are required, because only indirect methods are available, because so many diverse. factors must be taken into'consideration; and because wells vary so widely in such. respects as pressure, fluid propor'tionment and` distribution of strata. Only relativelyfew Wells, 30

say 2%, are ideal in the sense that factors may be readily isolated'in an unmistakable manner for identifying the encroachment levels; In the overwhelming majority: of wells overlapping complications and misleading factors are inevitable, whatever priorart procedure i's selected. Usually such exploration is a matter of trial and error in which some basic procedure is repeatedly performed in an attempt to develop some clue, how

ever indistinct and overladen, that will point to the water source.

An understanding of my invention may-be -approached advantageously by referring, first, to the more prevalent procedures heretofore employed. Each of the known practices is characterized by the traversing of the problematical bore hole, or a suspected portion thereof, by' a. single means that is'r'esponsive to changes in fluid character, a

corresponding indicating instrument being observed'at the surface. Various types of electrical indicating devices are employed, responding, for example, to changes ln'- the ohmic resistance, light transmitting properties or electrolytic properties` of the well uids.

1f the indicatingy device employed includes a water is saline, in vwhich case the conditioning 'fluid is usually fresh water, but may be ordinary mud or chemically treated mud.' The well fluids '10 are completely replaced by a column of conditioning fluid exerting sufcient static pressure to Y hold in abeyance flow 'from the well formations. Commonly, a tube is lowered into the'well l for fluid circulation to carry out the conditionl5 ing operation, after which the tube is partially Awithdrawn and the test` procedure initiated by swabbing conditioning fluid from'the well to approach step-by-step the point at which static ipressure of the conditioning fluid columnk balances formation pressure in the bore hole. The

point of pressure equalization must be approachedv cautiously and it is necessary to explore the bore hole with the pair oil/electrodes. after each swabbing operation to ascertain whether or not the resultant reduction in static pressure initiates well flow. Eventually the pressure predominance is reversed and the subsequenttraverse of the l borehole by the pair of electrodes indicates the Successive traverses of all suspected zones bythe indicating device are carried out, preferably, until substantially complete displacement` of the conditioning fluid by formation fluids is 35, indicated, swabbing alternating with testing when necessary. The resistance readings of the'successive traverses are tabulated and then translated into corresponding successive curves plotted against' well depth for careful study.

`The disadvantages of such a typical procedure may be Vclassified 'as follows: the excessive amount of time required for the test; the high cost of the test; the difllculty of obtaining ade quate information from the test; 'the high degree of skill required to conduct the test; the danger of losing control o1' the well; and, finally, the fact that the test may not be employed 4foran uncased well. 'I'hese disadvantages will be'` considered in order. f

the amount of swabbing required to 'approach pressure equilibrium is unknown, and since a lwell is lusually extremely sensitive as the critical point is\ admission of formation uids into the bore hole.

Such a test rarely iscompleted in less than two full days and often requires Weeks. 'Onereason that the test consumes so much time is that, since 4 ings,

` and, conversely,

mum pressure from thezcolumn of approached, time-consuming caution is abso-` lutely essential. The end sought is an optimum surge of formation fiuid from the walls of the bore hole into the column of conditioning Iiuid fluids, moreover, cannot be foretold, and since y the recording instrument is necessarily inoperato effect values of subsequent resistant measure- 5 ments of the well content. Either too slight ingress of the formation fluids or too violent ingress will hopelessly obscure the results and necessitate conditioning the well for a new start. The

unavoidable preliminary period of swabbing and 10.

testing for results, preceding any significant findis prolonged not only by the number of precautionary test readings necessary, but also by the fact that swabbing and testing may 'not be conducted simultaneously. The electrode cable must be completely withdrawn during swabbing, a test reading may not be made while the swab is in the well. If the wellmust be capped during the test, further delay is involved in the manipulation of the testcable through a packing gland at the surface. Even duringv the fruitful period `of cedure cannot be carried out rapidly because any suspected zone of the bore hole must be explored step-by-step in a time-consuming manner for i the notation of resistant values. Such tests are usuallycontinued until readings show the conditioning fluid to be completely displaced by intruding formation fluids and therefore are often unduly prolonged because tioning fluid to the test zone is favored by the fact that the whole fluid column in the well bore is in free communication with the test zone. Finally, repetitions of the Whole painstaking test procedure are necessary even under favorable conditions, because of reluctance to accept the `results of a single test as conclusive.

The expenslveness of the prevalent type of procedure under discussion is attributable, of course,

'a test is largely inherent in the test itself as wur now be discussed.

- In the first place, the procedure is fraught with misleading extraneous factors. Formation fluids, including salt water, that are driven from thebore hole into receptive strata under maxiiluid tend to return to .the bore hole `with drop in bore pressure to contaminate the conditioning fluid and thereby introduce false clues into reentry 65 the resistance readings. Such points of may be remote from the original points lof ingressv of the fluids. In addition, convection, diffusion, turbulence from movements of the test device, and conveyance of fiuid from one level to another by the test device cannotl be evaluated 7o directly or separately identified, since all these effects may influence resistance values as effectively as the formation fluids to which the test is directed. The-effect `of the particular swabthe test the protive at the moment of fluid release, no immediate clues for measuring the effect Jof the fluid release are presented. A violent initial surge of formation fluids into the well bore may `so agitate the whole test zone as to preclude the formation of any representative resistance pattern, or such a pattern if formed may be shifted bodily along the borehole by sustained flow before the4 test device can be lowered into the well. 'I'he human equation is a further consideration to be noted, since errors may arise in reading resistance values, in gauging the depth of the indicatlng device, or in translating4 the readings into graph form.

migration of condimore often than not,

in large part to the fact that time is taken out of given instant, whereas, in fact,

conditioning do bing operation that first releases formation gaps. A further consideration is Ithe chart vand each point on a so that no two points on the In the second place. even in the absence ofv false clues and inaccuracies, the data of the test may be inadequate because incomplete'. I have made the important discovery that phenomena of only fleeting duration incidental to the initial flow of formation fluid into the `well bore may often sufllce alone to indicate conclusively the points of salt water ingress, yet at such time in the usual test procedure no such indications are discernible because the test device is out of the,

well. The test data as heretofore acquired are based o nonlyl intermittent observation with substantial time gaps in which highly significant transient factors may occur entirely unnoticed. Even when a test operation is in progress-only one point is under test at any given moment. with the result that fugitive as well as sustained effects at other points'are completely ignored. This defect is more pronounced if time is taken .to explore the fluid column carefully in a test traverse, since such care increases the intervals between readings at any one well level.

lIn the third place, certain difculties arise in interpreting the graphically presented data of the test. especially since there is a conflict betweenthe necessity. on the one hand, of seeking positive clues in the indirect evidence, and the necessity, .on the other hand, of exercising cau- 45 tion and of discounting irrelevant or extraneousr forces.

'There is an undesirable tendency in readingsuch a graph to interpolate data in the gaps between the successive curves, a tendency to assume, for example, that there are gradual transitions from curve to curve, whereas indicative effects may in fact be lost in one of the time a mental tendency to regard each of the successive Igraph curves as representing .the entire test zoneiat a no line on the chart reflects a momentary well condition. Each line is separated in time from adjacent lines of given line is in time sequence to every other point on the line, Whole chartare concurrent. It isnecessary, then, to avoid as unwarranted any assumption that any simultaneity whatsoever is represented by the chart.

The danger of losing con-trol of a Well in the course of a test is serious if high pressures prevail in the formation fluids. Such a well must be initially overbalanced by a, fluidv column of considerable Weight. If they lowering of that column in the course of a test isoverdone, the conditioning fluid will be forced upward out of the well, preponderance of the well pressure rising rapidly. The unbalancing may progress too far expedite the test, especially if the reversal of pressure occurs while a swab is in operation.

A further respect in whichthe test procedure under discussion is far from ideal isthat it is not applicable to uncased wells. In the rst place,

any substantial lowering of the column pressure for test purposes.; and in the second place, an operator dares not risk irreparable damage -to the walls of the bore hole by repeated traverses of a testing device. To make a test for accurately locating the troublesome points of water entry it has been necessary heretofore to case the bore hole, with no assurance beforehand that the well will not have to be abandoned, or that another string ofcasing will have to be inserted in the well, because of too extensive water intrusion.

Finally, it is apparent .from the.v disclosure to 't this point that the test proceduredescribed is4 `difficult, complicated, and full of pitfalls.

-most of the heavier cost'items heretofore involved. l

With respect to the test data, it is my purpose to concentrate on primary factors, to minimize but continuous .flowf'rom the formation' walls the fact that the column of drilling fluid in effect supports the walls of the uncased hole precludes 'conception of continuously and vsimultaneously the test zone. One of the more specific objects of my invention, therefore, is to provide adj ably controlled means for releasing the uid pre sure in a test zone at a gradual andv uniform rate y to attenuate the test curves and in effect to magnify anomalies on a time scale.

It has been pointed out heretofore. thatcertain false clues arise from, the fact that in the usual vpractice the test zone is in communication with thewhole column of fluid in-the well. An other of my more specific objects, then, is to provide a test procedure in which the suspected zone is'k entirely isolated from the main body of the fluid column whereby all test factors lare localized,

Broadly, my invention is characterized by the recording' changes in fiuid character at a plurality of points in a test zone under conditions that simulate or approximate normal Aproduction ow;

l It isglmy further object, then, toprovide meansv for such simultaneous recording of data ata plurality f levels and to provide for establishing Y a representative flow status. Av feature of my invention is the provision for an unbrokenrecording period that includes the moment of flow l Figs. 1 and 2, taken together, show in vertical f section the preferred formof my, apparatus infstalled ina bore hole, the lower 'end of the apfalse-clues, to secure continuous data under' acf tual flow conditions, to reveal simultaneous as well as sequential relationships, to produce a simple and easily interpreted chart,` and to eliminate substantially the human equation.

Another broad object in mind, is to-provide a test procedure that involves no risk of letting a well blow out.

One of the more important general objectsof my invention is to achieve a test procedure that is safely applicable to uncased bore holes, whereby the character and exact location of water en-` croachment may be determined without the necessity of investing in casing for the bore hole.

This feature of myinventionwill decrease in aterially thecost of speculative drilling in untested elds. a

A further broad object of. my invention is to reduce the test to a relatively simple procedure that may be conducted for accurate and conclusive results with a modicum of skillon the part of the/operator. 1 v

In the preferred form of my invention itis my object to provide for performing the test, largely initiation so that effects associated with the firstv surge of formation, fluids may -be studied..

Other objects and advantages of my invention t will `b eapparent inthe course' of my more detailed description tol follow,taken with my ac companying drawings.

Inthe drawings:

paratus being shown diagrammatically;

' Fig. .3 is an enlarged fragment of Fig. 2

Fig, 4 is an enlargedzvertical section vof the-lower end of the apparatus showingthe construc-l ti .Fig. 5 /is a transverse section taken asindieted by themes-5 of Fig. 4;

Fig.-6 is a side elevation of the case'for refcording instruments employed in' the preferred of my invention andv r v \Fig. 1 3'isk a similar view of -the Ywell in the` Y by completely automatic means and to dispense with the necessity for operating through a packing gland at the surface and the necessity for manipulating reels, cables, and similar paraphernalia in the course of the test.

In a test'of the character I have inmind, the significant clues are anomalies in the resistance curves. I have discovered that -such anomalies are -often precluded or escape notice entirely if` the flow of formation iiuid into the bore 'hole occurs too rapidly, as is often the case when abk swab is used to lower the uid level, whereas such" anomalies will 'stand out in the record if the form of my invention, the case being broken awayto reveal its interior;

Fig. 7 isa ytransverse section taken as indicated by the line 'L -1 of Fig. 6;

tem

Figs. 9, 10, and 11 -are representative graphs produced by the recording means; y

\Fig. 12 is a diagrammatic representation of a 'cased well being conditioned for a second practice course of my second test procedure. e

` Figs.v 1 and 2 show an uncased bore hole, the] i lower portion of which is Aof reduced diameters In a typical situation it is known that both water and` petroleum fluidsare produced in this y lower restricted portion of the bore hole 20 and the problem is to ascertain the points' of 'water ingress. The apparatus for exploring .this lower portion of the bore hole 20 is incorporated ina string 2| of drill pipe or tubing, the string being divided into an upper section and a lower section that are telescoped together for relative longitudinjal movement. The top of the string 2| is curves are attenuated by providing for restrainedg Icharge pipe 23v controlled by a. valve 24. At some f I point in the `string 2 I is a closed as! by ,a `plug'22 and is .provided with a dis.`

flow bean 25 to restrain upward flow therethrough.; y. n l

on of parts' illustrated diagrammaticallyin Fig.

' Fig, 8 is a wiring diagram of the recordingsys-y 'I The upper section of the string 2l is' generally designated 28 and the lower section is generally designated 29. Toward the lower end of the upvper section 28 is a valve, generally designated 80, `comprising a seat member 3| and a valve member 32 having a long rod-like stem 33 extending axially down into the lower section 29 of the string. This valveis continuously urged toward closed position by a suitable spring 34 acting be tween the seat member 3| and a collar'85 on the stem.33.

vThe upper end of the lower section 29 of the tubing string terminates in a bushing 31 embracing the valve stem 33 and having a plurality of bores 38 for the passage of fluid. The bushing v31 is mounted onthe upper end of a tubular guide portion 39 yof reduced diameter that in lturn is mounted on a'guide portion 40 of intermediate diameter, and just below the'guide portion 49 is a third guide portion 41| of relatively large diameter. The upper section 28 of the tubing string has elements complementary to and slidingly cooperative with these three guide portions, namely, a guide bushing 42 embracing the guide portion 39, a tubular portion 43 embracing vthe guide portion 40, and, finally, a terminal portion 44 embracing the guideportion `4|.

The lower tubing section 29 carries a rathole packer 46|) of any suitable type that is adapted 'to engage the upper endof the restricted bore 20, thereby to form with the tubing string an effective seal between the reduced bore 28 and the major portion of the well above the zone to be tested. Somewhere in the lower tubing'section 28 either above or below the packer 89 isv an instrument cylinder 62 incorporated in a length of tubing ,63. The annular space 64 between the instrument cylinder 82 and the wall of the tubing 83 provides a longitudinal passage'for fluid through the tubing pastthe cylinder, the passage communicating with bores 66 and 66 at its upper and lower ends respectively. The contents` of the instrument cylinder 82 are dependent upon the type of means responsive to changes in iluid character that is elected for the test. Any suiti able responsive means may be employed, including photoelectric means to record the light transmitting character of the .fluids under test, but I r prefer to carry out my test by means responsive to changes in the ohmic resistance of the fluids being explored. The instrument cylinder 62 in The described sliding joint `between the two sections of the tubing string is sealed by suitable packing. For this purpose a ring 46 on the` lower tubing section 29 is mounted on the lower tubing section at the upperend of the guide portion 40, and the guide portion 40 is provided with an annular flange 41 spaced-belowtthe 'ring 46, the ring, flange, and guide-portion 48 thus forming-a space to receive a packing ring 48. A second packing ring 49 embracing the guide portion 40 is retained by a bushing 58 engaging the tubular portion 43 Aof the upper tubing string.

The annula space 62 around the guide portion 39 between the guide bushing 42 and the plate 46 will change in volume with relative movement' bushing 31 to 'unseat the valve member 32. `It

is desirable that relative movement between thev the preferredform of my invention houses a -recording c`ase 88, a battery case 69, and a case 19 for means to convert direct current into alternating current.

Since I prefer as a feature of my invention to operatively relate the valve 3l! with the recording means, I extend the valve stem 33 into the upper f end of the instrument cylinder 82, the valve stem extending through a suitable packing gland 1I.

At the lower end of the instrument cylinder 62 is a second packing gland 12 embracing a conductor cable 13 15. The cable 13 includes conductors for a plurality oi pairs of electrodes, there being in the form of my invention shownln the drawings six pairs o f electrodes, generally designated 16a to that extends downwardly into a terminal tube 1'4 having numerous perforations y 'I'he pairs of electrodes 16 are shown di'agram-' 4 matically in Fig. 2 and may be mounted in the perforated tube 14 in any suitable manner. A feature ofthe preferred form of my invention, however, is the yconception of mounting thepalrs of electrodesforadjustable spacing in the per- -two tubing sections be limited in a positive manner to prevent opening of the valve 3|).until the test apparatus is installed ih the bore hole, but subsequent to such installation sufficient downward .movement of the upper tubular section against the stationary lower tubing section must be permitted for operation of the valve 30. In my preferred arrangement the lower -tubing section is provided with a radial lug 66 at the guide portion 4l to cooperate with a slot, generally designated 51, in the terminalI portion 44 of the upper tubing section r28. This slot has a portion 58of too limited vertical extent to permit opening of the valve 30 and has 'a second portion`59 that will permit relative movement sufficient to operate the valve, the lug being carried from one slot portion to the other by approximately a quarter turn of relative rotation between the two tubing sections.

forated tube 14. A suggested construction may be understood by reference to Fig. 4; In this suggested construction two parallel support cables 1S and 80 are suitably anchored in longitudinal disposition in the tubing 14. A plurality of electrode carriers 8| having tubular portions 82 and 83 slidingly embracing the support cables 19 and v8!) respectively are adjustablyretained at selected positions by set-screws 84 releasably engaging one of the cables. Each of the carriers 8|.'has a pair of arms Btl-supporting in spaced relation apair of theelectrodes 16. To insure maintaining the electrodes in fixed positions uni formly spaced from the walls of the perforated tube,.the' cable `8l) may be bound to the wall of the tube by spaced wire'ties'81.

Electrical circuits that may be employed in my apparatus are shown'diagrammatically in Fig. 8. .A battery housed in' the battery casing 69 'energizes means in the case 19 for producing an alternating current.. For example, the battery 98 may be hooked up through wires 96 with an oscillating circuit that is generally designated by the numeral in Fig. 8.v The particular oscillating circuit shown, which is a well known arrangement that includes a vacuum tube 91 (Type 30) and a variable condenser 9 8, is connected with the primary terminals of a transformer 99 and is controlled by a switch 94. One of the secondary terminals of the transformer 99 is connected 'through a wire |04 with one electrode of each of 'the pairs of electrodes 16 and the other secondary terminal of the transformer is connected through a wire to a series of milliammeters |06, each of the milliammeters being connected in turn latching position, the bell-crank |43 is held in an elevated lposition by" asuitable leaf spring |45 mounted on a bracket |46, the leaf spring carry- `ing a latching lug |41 on its upper surface. Pivoted above the leaf Isprir 1g.|45 on a suitable behind the lug |41 to hold the latch spring dethrough a wire |01 with the second electrode .of

milliammeters, the plurality of lamps being en ergized by an independent circuit including a battery means ||1,0, leads and |2, and a light switch ||3. I

'I'he recording instrumentalities can be arranged in the recording case 68 as indicated in Figs. 6 and 7. Two dry cell batteries |5 constituting the previously mentioned battery means IIIJ forv energizing the lamps |09 are secured in the recording case 68 by an arcuate longitudinally extending wall H6. 0n the opposite side of the recording case isa longitudinal light chamber, generally designated |1, having a somewhat arcuate longitudinal wall ||8, a plane longitudinal |23a-|23f. InA each of the recording compart- 'l ments one of the lamps |09 is so'positioned with respect to a needle or indicating arm |25 of the associated milli'ammeter |06that the shadow of the needle intersects a suitable recording slot |26 in the wall H8. Photograph-ic film |29 from a supply spool |30 journaled in bearin'gs |3| is fed Aaround the Awall ||8 o'f the light chamber ||1 past the series of recording slots |26 to a driven lspool |32 journaled in bearings |33. Integral with the spool |32 is a gear |35 that is driven through a train of gears |36, |31, and |38 by clockworks, generally designated |39, having a winding key |40.

While the test apparatus is being installed in a bore hole, it is necessary that the clockworks be idle and it is desirable that the two switches 91 and ||3 be open. -During a test period, however, that is initiated by closing of the valve 30 in the tubing string, it is necessary that the clockworks actuate the film and that the two switches 4 be closed. 'A suggested mechanical arrangement for operatively 'relating the; recording instruments with the valve 30 may be understood by referring to Fig. 3. I f I The clockworks. |39 is controlled by an upwardly extending control arm |42, whichiin the position shown in full lines in Fig. 3 latches the clockworksagainst movement, and in the dotted line position of Fig, 3 permits the clockworks to actuatev the spool |32 and thereby to draw the film past the recording slots |26. TheY control .A arm ,|42 may likewise operate both the switches 91 land ||3 if desired. In the form of my invention `shown in the drawings,'however, it is contemfplated that'- only -the switch ||3 for the lamp pressed whenever the latch spring is flexed downwardly suiilciently by the end of the valve stem f 33. The latched position of-the leaf spring and the corresponding position of the latchingng'er are indicated by dotted lines in Fig. 3.

Tl'ie leaf spring |45may conveniently 'serve as the movable member of the switch 91. For'this purpose a switch contact' |5| is mounted on the lower side of the leaf spring |45 and a cooperating fixed contact |52 ism'ounted therebelow on a suitable fixed arm |53, the two contacts being l connected to the associated circuit wires 96. It is apparent that suilicient downward movement `of the valve stem 33 will not only release rthe clockworks |39 for operation, but will also close vboth the switches 91 and ||3, the clockworks and the switches being thereafter operative for a test period independently of subsequent movements on the part of-` the valve stem 33.

Preliminary to the operation of mydevice, it is not always necessary to introducespecial conditioning fiuid into the bore hole, especially'if there is a suflicient ohmic reistance differential between4 the valuable fluids and the encroaching water. In the usual procedure, however, conditioning fluid, which may be in the form of plain water, will be introduced into the well to'a height .y y

to overbalance formation pressures and thereby to hold in abeyance formation flow. vTo securel bracket |49 is a freely rotatable latching finger' |50 that rests up'on the leaf spring |45 but dropsk the requisite hydrostatic pressure, relatively heavy face with the lug 56 ofthe lower tubing section 29 engaging the restricted vertical portion 58 of the slot 51 in the upper tubing portion 28 of the string. An unexpos'ed roll of film on thespool r |30 ready for movement `past the recording slots Y |26, but the control arm .|42 is in its upper posi- .tion to hold the film actuating mechanismin abeyance and both1thejs'witch 91 controlling..

current to the electrodes and the switch ||3.fc'e`n trolling the lamps |09 are in open position. The lower section 29 of the tubingstring is suspended from the upper tubing section 28 by engagement of the lug 66 with the slot 51, but the limited Avertical dimension of the portion* 58 ofI the slot` prevents suicient relative axial movement bey1 Vtween the two sections of tubing to cause the I valve 30 toopen or to cause the valve stem 33 to initiate operation of the recordingl system.

The whole stringfof tubing 2| initially is empty except for atmospheric air.

lowered into the column of iiuid in the well bore some liquid will be forced into the perforated ff".

tube 14 and perhaps upwardly in thetubing string above the packer 60, but the valve` 30 will remain closed to prevent any substantial upward iiow'. When the packer60 seats into the top of -the .reduced portion 20 ofthe bore hole, static pressure of the fluid column abovel the packer will act upon the upper end ofthe packer, the packer then becoming an effective annular seal maiorportion of the fluid column in the .-bore hole. 'i i As the stringv is.

1 to isolate the test Zone below-the packerfrom the When the test apparatus is ready for opera- 1 by Figs. 1 and 2, the upper tubing string 2l is manipulated to rotate the slot 51 intoa position at which the lug 56 is in the relatively long ver' tical portion 59 of the slot. The upper section 28 of the tubing string isthenvmoved downwardly to open the valve 3|! andsimultaneously to initiate operation of the recording mechanism, the collar 35 of the valve stem 33 striking the bushing 31 to open the vvalve and the lower end viously driven into receptive strata of the test zone begin to ow into the test zone as soon as the pressure below the packer 60 drops below formation pressure, initial formation flow usually following opening of the valve 30 by only a few seconds. It isimportant to note, however, that yoperation of the recording system is initiated' immediately so that the rmoment of initial formation iow lies within the recording period.`

One of the important advantages of my test method is that actual flow conditions are simulated in a relatively short period. If, the whole bore hole were in communication with the test zone 'to permit extensive counteriiow, a consid-` erable volume ofow would be necessary to clear the test zone of conditioning fluid and establish vstable flow conditions or a relatively stable ow pattern in .the test zone for reflection in the testrecord. By isolating the test zone in the manner described, however, Iam enabled to displace the conditioning fluid completely from the test zone and to attain representative flow conditions therein within a relatively short period.

' Because only a relatively small volume of well uid need be displaced for a conclusive test, because I dispense entirely with any preliminary groping for a criticalhydrostatic pressure, and because the test continues unbrokenly without interruption of flow for manipulation of test devices and without interruption of recording for manipulation of flow control devices, I am enabled to accomplish my object in a relativelyl short recording period. For example, I may elect to have the film and the associated recording mstmmentauues in operation rr a period of only twenty minutes. Y t

In the test period, whatever the length of tim decided upon, I propose to reflect in my records the characteristics of three successive stages of flow in the test zone, each of which stages as reected in the records, considered alone or in the light ofthe other stages, points -to the information sought by the test. The first of these stages is the initiation of well formation flow, this stage including the momentary effects of such flow initiation. The second stage of flow is the transiat` the beginning of the test is completely dis'- placed from the test zone. The third 'stage is slgnalzed by the attainment cfa relatively stable now pattern simulating actual production conditions. In this' thirdstage the test zone is occupied entirely by formation fluids streaming through the test zone in a flow pattern deter- `mined by the distribution of points of ingress.

relative pressures and volumes, and the char'- acteristics of the different, formation fluids.

A feature of my invention is that by control-` tion stage during which the fluid in the test zone ling the rate of flow from the test zone, for example, by employing theilow bean 25, I may control the rapidity with which these stages succeed eachother and the rapidity. of the effects involved. Within a .twenty-minute recording vperiod `I may readily cause all three stages to appearon the photographic record and yet retard the sequence of effects to attenuate the recorded curves for clarity of reading. Control over the degree of attenuation in the resistance curve is of especial importance in high pressure wells, because under the conditions of the usualI On each filmare six curves falling in fixed horizontal bands representing levels A to F corresponding to the location of pairs of electrodes 16a to '16! respectively.

In Fig. 9, for -the first two minutes of the recording interval, curves A, B, C, D and E fluctuate in the manner` that characterizes the inflow into the conditioning liquid of gas and oil from productive strata; while the curve 'F during the initialtw'o minutes of recording is constant at a relatively high value that characterizes the conditioning fluid. At the end of the two minutes, however, curve F dropsoilgin a definite manner yindicating the inflow of salt waterv and by the end of the i'lrst four minutes of the test becomes stable at a low resistance value indicating cornplete displacement of; the conditioning fluid from the corresponding well level. By the end of five minutes, it is apparent that salt water moving upwardly from the we'llwlevel F has definitely` depressed the resistance values of curveE. In sequence thereafter curve D is definitely depressed after six and one-half minutesof recording, curve C after ten minutes, curve B after fourteen minutes, and curve A after eighteen minutes of recording. I'he-chart shown in Fig.

9, then; clearly indicates that water is entering the well bore in thevicinity of the well level at which the electrodes 16! are located.

In the -record represented by Fig.l10, it is apparent that until near the end of the first two minutes of recording, the ohmic values\of all the x curves correspond to the relatively high resistance characteristic of conditioning fluid. y At the two minute point, however, a sharp and extensive dropln the value of curve C indicates vthe sudden ingress of a substantial dow of salt water ing upward through the test zone to mingle with the salt water at the well level represented by curve C cause fluctuations in the curve C but the f curve C persistently seeks' a low ohmic value indicative of continued saltwater ingress. After eight minutes of recording, curve B reveals some inflow of oil and gas at the corresponding well level, but the resistance values of curve B are soon thereafter depressed by upwardly flowing salt water from the level corresponding to curve C.

Curve A indicates no formation l' flow of any\ 2,248,982V kind, but toward the end of the test-period dropsv sharply as salt water reaches'the corresponding Well level.

`representedby Fig. indicates salt water ini sponding toelectrodes 161.

`trusion at the level corresponding to electrodes 16c,just astherecords represented by Fig. 9 indicated salt water intrusion at the level \corre In all of these tests, the tendency ofI salt. water to diffuse through the liquid content of the te'st zone must be kept in mind, the rate of diffusion being greater in a downward direction than in an upward direction. -If the rate of flow from the test zone is severely restricted by the flow bean employed, diffusion may affect and even dominate the resistance curves of the record. The effects of diffusion have been troublesome and confusing in all prior art test procedures It is apparent, then, that the record 'curves B and F are horizons of impervious shale;v

that some gas issues from a sandy shale atff level corresponding to curve E; that curve Dfcor-'j V responds to an active production level; that curve y C has a formation producing oil at a somewhat" reduced pressure; and that salt water Yis intrudlY ing to a serious degree in thel neighborhood of because the extended time required by the prior f procedures has favored development of diffusion effects. In one practice of my invention, as performed by the apparatus described, I, in effect, isolate diffusion eiects and study such effects y under static and substantially quiescent conditions not heretofore attained in a test procedure.

In this latter practice of my invention, I open the valve in the tubing string for only a very short time at the beginning of the recording period and then either keep the valve closed during the rest of the period or open the valvefor selected time intervals, the valve movements ,being carefully tabulated for consideration with the correl sponding photographic record. It will be apparent that since the recording `system described above functions independently of the valve after it is started by the rst valve movement, the api paratus is adapted to the procedures here suggested. f n

As an example of a record based primarily on diiusion effects, attention is directed to Fig. 11.

` Such a chart would result from shutting off flow from the test zone of a well of a certain character after three minutes of iiow, no further flow from the'test zone being permitted throughout the.

period under observation. The chart shows. that salt water entering with a rush at the level corresponding to curve A' provided a body of salt water at the corresponding well level and that inow of salt water also occurred at the level corresponding to curve E. Curve A remained depressed throughout nearly the whole of the quiescent recording period, recording migrating oil and gas-only at the end of the period. The values of curve E, however, did not remain depressed and the fact that curve E in the latter half of the test period persistently sought higher levels reveals that the salt Water ingress at the corresponding well level was not permanent. In other words, the formation at the level corresponding to the electrodes 16e is a receptive,

downward "diffusion later'aiected the average values of curve C. Fig. 11 would be interpreted, then,` to indicate that levels' corresponding to the level represented by curve A. It is to be noted in contrast to prior vart test proceduresfor I measuring diffusion thatI insure complete cessation of flow' from the test zone during the time interval of the diffusion test and that I elimi-` nate all mechanical causes for agitation or turbulence in the `fluids of the test zone in that time interval.

It will be further noted that the recorded values common to a vertical line represent simultaneous conditions at the corresponding well levels. Important also is the factthat any point on one of the vcurves may be evaluated by comparison with the curve as a whole. In other words, it is apparent at once whether a given value shown on ar curve isrepresentative and significant or transient and not significant. Continuityof recording throughout the test period,

then, permits me to differentiate readily primary effects from secondary effects.

yIn the older methods resistance values. are taken at successive moments at successive levels.

It is apparent from Figs. 9 to 11 that a great many of such random values obtained by traversing the well zone withA a single indicating device would be necessary to reveal the trend [of the` values at the various well levels in the test zone and that significant effects escape detection. y k

During the previously. mentioned third stage of flow in the test zone whenproduction ow is simulated, the character` of the recorded vcurves will clearly reveal the location and extent. of water ingress. In suchcase no conditioning Afluid may Ibe necessary.` For themajority of tests, the initial presence of conditiningifluid is def sirable but a feature of 'my invention is that since' would inevitably the test zone is isolated from the major portion of the fluid column in the well, it may not be necessary to have the conditioning fluid consti# tute the whole liquidcontent of the well. This peated tests.

fact is an important advantage inrconducting're- After one test has been made, it is possible to vrepeat the test after a relatively short pause for lowering altube into the test zone for pumping only suflicient conditioning fluid for displacement of well fluids from the conditioning zone, the fluid state of the` well above the test zone being largely ignored.

Thefact that a test may be repeated conveniently with no considerable loss `of time; and the fact that a construction such as shown in Fig. 4 4enables me readily to redistribute the electrodes,y enable me to proceed.' `first, to

bracket the point or `points of salt water in-`l gress. and then with a second morewcom'pactY arrangement of the electrodes to explore indicated levels more intensely for more precise information. In other words, I may in a rst test run have my pairs of electrodes spaced at relaf tively widely separated levels in the test zone to' ascertain only approximately the' level or levels of water ingress, and then in a following test run Q have the electrodesspaced at relativelyishort a restricted portionof the bore holelsuggested y'lli vertical intervals for concentrated exploration of by the record of the rst test run. Such a procedure will bound a salt water horizon within kpacker to isolate the test zone.

closerdimensions than heretofore possible and often will make it possible to block on? a troublesome strata without precluding ow from an adjacent productive formation.

V the substitution of a wall packer for the rathole type of packer.

While the procedure heretofore described is preferred because of the several advantages derived from isolating the -test zone and from reducingthe volume of fluid involved in the testit will be clear to those skilled in the art that my invention may be practiced without employinga One such procedure, for example, may be understood by referring to Figs.12 and 13, Fig. 12 showing a well l in the preparatory stage of the test, and Fig.- 13

showing the well in the course of the test procedure. The major portion of the bore hole is protected by casing |60, the zone to be tested lying in the lower uncased portion |62 of the bore hole into which extends the usual perforated liner |63.

Preparatory to testing sucha well a string of tubing |64 is lowered into the test zone and the top of the well is sealed off. At the top of the well the tubing |64 communicateswitli a pipe |65v controlled by a-valve |66 and the annular space between the casing |60 4and the tubing |64 communicates with a second pipe |61 controlled by a Yvalve |66. All the well fluids in the bore hole may be readily replaced in a well known manner by simply pumpingconditioning uid into the well through one of the pipes |65 or |61 and permitting `iluid to flow from the well through the other of'these-pipes until the discharged'iluid is substantially free of well fluids. The tubing |64 is then withdrawn to a level above the test zone as shown in Fig. 13, and a test cable carrying a plurality of, pairs of electrodes |1|a to |1|f is lowered into the well.f Any suitable arrangement may be employed `for making the cable taut. For example, a weight |12 of suitable mass may be attached to the cable. The well will be sealedby employing a packing gland '|13 where the cable enters the tubing. V

A condition is then sought that will simulate in the test zon'e normal production flow. To this end I may introduce a gas througheither pipe |66 or pipe |61 to attain a status in which flow of formation fluids into the test zone is held in abeyance bythe weight of the conditioning fluid in the well plus the pressureof gas on the fluid, the fluid column itself not being of suiiicient weight alonerto overbalance formation pressure. To achieve this state, it will usually be necessary, first, to introduce enough conditioning fluid to overbalance formation pressure while the l test cable is being installed and then, after sealing the top of the wellrto introduce gas-through one of the two pipes |66 and |61 to a suiiicient extent tc force a considerable volume of the conditioning fluid out of the wellthrough the other pipe. i

After the'desired combination of gas pressure and liquid weight is achieved,'it is necessary for I initiation of ilow in the test zone merely to open whichever one of the valves 66 and |66 com-A municates with the compressed gas body above the liquid column. For example, if the requisite amount of gas is introduced through the pipe |61 to'force' the requisite amount` of conditioning fluid out of the well through the pipe |65, subserquent closing of the valve |66 to shut oil' the pipe |65 and partial openingof the valve |68 to open the pipe |61 will cause the liquid in the well to take, say, the level |16 in the tubing'l64 and the level |16 in the annular space around the tubing. Continued release of gas subsequently through the pipe |66 will eventually reduce static pressure in the test zone sufficiently to permit formation fluids to flow into the test zone. If desired, flow may be stopped immediately to record the results of diffusion in the test zone, or flow may be continued until a relatively stable flow pattern is indicated.

Throughout such a test procedure, the plurality of electrodes is stationary in the-well and the test procedure is carried out without interrupl tion, it being necessary merely to manipulate the valve that controls release of gas from the well, the indicating instruments IBM-IBM corresponding to the various pairs of electrodes being continuously observed by the operator for guidance in manipulating the gas valve. Here again automatic recording will be found advantageous and the mechanism heretofore described may be employed. This second procedure includes ali thev advantages over prior art methods that inhere in the fact that the electrodes are stationary, that inhere in the fact thatjlow is under close control, and that inhere in the fact that effects in the well are observable continually throughout the test. period. It will be apparent to those skilled in the art that several of the well known gas-lift methods may be employed to cause and maintain well flow in carrying out my methods.

My invention may also be practiced with the apparatus of Figs. 12 and 13 by ilrst conditioning 'a well and' then, with the top ofthe Well open.

static pressure drops below formation pressures. Flow'of formation fluids into the tial period if the well is unbalanced by a subplurality of electrodes may then be lowered into the well for continuous observation over a period of ow to ascertain the pattern .of flow in the test zone. 'I'he latter practice, however, obviously lacks several .important advantages heretofore noted and involves considerable Vrisk of the well blowing out, especially if thel well has relatively high formation pressures. f'

It is to be wide/ly 'and that any test procedure must be adapted to the particular conditions confronted. The basic principles involved, however, will .be apparent to those skilled in the yart from 'my .foregoing disclosure. and I reserve the right to all departures from the procedures set forth and all modificationsand changes of the apparatus described that fallA within the scope of my ap-A pended claims.

mation fluids thereinto; temporarily lowering the l pressure of said conditioning fluid long enough to permit representative bodies of formationfluids, to enter. the borehole, but not long enough to cause substantial displacement or substantial now of the bodies; andrecording fluid character test zone will l then commence and will continue for a substanemphasized that test problems [vary a`,a4a,es2

-well'to respond to changes in uid character continuously 'and simultaneously at a plurality' of spaced points in said test zone to reveal. progressive diifusion from said bodies as centers.

2. A method or determining the points pfingress of formation uids in a bore hole, including the steps of: loading said bore hole with fluid to overbalance formation pressure sufficiently to prevent flow of formation fluids thereinto; sealing off atest zone of the bore hole; drawingoif fluid from said sealed test zone to initiate flow of formation uids thereinto; and recording fluid character continuously and simultaneously at a plurality of spaced points in said test zone in the course of said flow of formation uids.

3. A method of determining the relative character and location of formation fluids' communicating with an uncased bore hole that isloaded with a fluid column supporting the walls thereof, said method including the steps of:l sailing on a test zone of the bore hole; providing communication to atmospheric pressure .through Said fluid column from said test zone, thereby lowering the pressure in said test` zone sufciently to initiate flow of formation uids thereinto Vwithout lowerf ing the pressure of said fluid column against thebore hole walls outside of the test zone; and r'ecording fluid character continuously andsimultaneously at a plurality of spaced points'in said test zone in the course of said flow of formation fluids.

4. A method as set forth in claim 2 in which the pressure in the 'te'stzone is lowered long enough to permit representative bodies of formation fluids to enter the bore hole, but not long enough to cause displacement or substantial flow of the bodies, whereby progressive diffusion from said bodies as centres will be revealed by said recording.

5; A method of determining the relative character and location of fluids communicating with a bore hole that is loaded with a fluid column, said method including the steps of: sealing off a test zone of the bore hole; providing a channel to atmosphere through said fluid column from said test zone, thereby lowering the pressure in said test zone sufficiently to cause flow of formation fluids thereinto and upward through the channel; and recording fluid character continuouslyand simultaneously'at aplurality of spaced points in saidv test zone in the course of said flow offormation uids; and restricting said channel to attenuate the eects recorded.

6. A method of employing automatic recording means responsive to changesiin fluid character for the purpose of determining the relative character and location of formation uids communicating with a well bore hole, 'said method including the steps of: lowering a plurality of said autosimultaneously at a pluralityof spaced points in a test zone ofthe well for the duration of a test period; sealing off said test zone; providing a channel through vsaid fluid column from said test zone to thevl surface of the well; and releasing fluid from said sealed `test zone through saidy channel to cause formation fluids to flow into the 'test zone during a test period.

8. A method of employing means responsive to changes in fluid character for the purpose of de- -te'rmining the relative character and points of ingress of formation fluids in a bore hole, including the steps of: loading said bore holewith liquid to overbalance formation pressure sufflciently to prevent flow of formation fluids thereinto; placing in the well at vertically spaced positions a plurality of -said means responsive to changes in fluid character; sealing off said bore hole after said meansl are in position; introducing compressed gas into thev boreand drawing off a portion of said liq-uid to attain a condition in which a liquid column combined with gas presto initiate flow of formation uids into the Well;

observing the effects of such release on each of said responsive means continuously for the dura- 1 Y ltion of a test period; and then introducing sufficient liquid into the well to hold in abeyance formation flow by liquid pressure alone to permit unsealing the bore hole for withdrawal of said responsive means.

9. A method as set forth in claim .8 in which guidance in the' release of the gas from the well is obtained from observing the actions of said responsive means.

l0. A method of employing means responsive to changes in fluid character for the purpose of determining the relative character and points 'of ingress ofs formation iin-ids in a bore hole, including the steps of: simultaneously recording changes of fluid character at a plurality of vertically spaced points in a test vzone of thebore hole while the static pressure of uid in thel test zone is sufficiently belowformation pressure to permit sustained flow of formation fluids matic recording means into the bore hole'into complete isolation from the surface of the well to respond to changes in uid character I simultaneously at a plurality of spaced points in a test zone of the well for the duration of a test-period;

. and holding fluid pressure in the bore hole'below formation pressure to cause flowy of formation fiuids into said test zone duri-ng said test period. i

column preponderant over formation pressure,V

said method including: lowering a plurality of said automatic recording means into the well into complete isolation from the surface of the into thebore hole, thereby bracketing a portion of the test zone in which ingress of aV selected formation fluid occurs; and then simultaneously recording changesjof fluid charac-ter at closer spaced .points within the bracketed .zonek while the static pressure is low enough to permit sustained Vflow of formation iiuids into the bore hole.

l1. An apparatus for determining the points of ingress of formation fluids in a well-bore hole, comprising; a plurality of means each responsive to changes in fluid, character` immediately a d jacent each of said means; means tosupport said responsive means stationary at spaced points in a selected zone of the bore hole for the duration f a testy period; and indicating means "responsivel to each of said responsive means to reveal changes in said iluid-character.- r

l2.' An apparatus for determining the points;

of ingress of formation fluids in a well bore hole,y comprising: a plurality of r'neanseachv responsive to changes-in fluid characterimmediately adjacent each of said means; means to support vlsaid responsive means stationary at spaced points in a selected zone of the borehole for the dura tion of a test period; and means operatively connected to each of said responsive means for conn-l tinuo'usly recording responses thereof during said test period.

13. An apparatus for determining the points of ingress of formation fluids in a well bore hole,

comprising: av tubing string adapted to extend into a test zone of a bore hole; a packer embrac- -ing said tubing string to seal on said test zone:

a plurality of means responsive to changes in uid character carried by said tubing. string at spaced fixed .points relative thereto positioned to lie within said test zone: and indicating means responsive to each of said responsive means to reveal changes thereof.

14. An apparatus for determining the points of .ingress of formation fluids in a'well bore hole, comprising: a tubing string adapted to extend` into a test zone of a bore hole; valve means to \1 control upward dow through said tubing string.

\ changes thereof.

15. An apparatus as set forth in claim 14 in which said tubing is embraced by a packer to seal off said test zone.

16. An apparatus for determining the points of ingress of formation fluids in a well bore hole. comprising: a tubing string adapted to extendintb a test zone of a bore hole; valve means to control upward flow through said tubing string, said valve -means being normally closed and b'e. ing adapted to be opened when said tubing is installed in a bore hole; a plurality of means responsive to changes in fluid character carried by said tubing string at spaced nxed points relative thereto positioned to lie within said test zone to be affected by uids flowing from said test zone into said tubing; and means carried by said tubing to operate at a subterranean position for continuously recording the responses of each oi zone into said tubing; a packer embracing said tubing to sealon said test zone; and means carried .by said tubing in the lower half thereof for continuously recording the responses of each of j said responsive. means through a test periodi'olf' lowing opening of said valve.

l 21. Amethod of determining the reistiveehr;

acter and points of ingress of formation fluids in a bore hole, including the steps of sealing off a test zone at thelower end lof the bore hole from the maior portion of thebore hole with the static pressure of the iluid therein above the formation pressure to prevent formation flow: vreducing the static pressure in said zone below formation pressure to initiate now of formation fluids thereinto while the. .test zone `remains sealed; and simultaneously recording fluid char acter changes at a plurality of spaced points in said test zone over a period of time including' the moment of said flow initiation.

22. A method of determining the points of ingress of formation fluids ina bore hole, including, the steps of: loading the bore hole with a column ofcoriditioning fluid at pressure to preclude now. of formation fluids thereinto; sealing on' a test zone of theA bore hole to isolate the test zone from the major .portion of said column; providing communication to atmospheric pressure through said fluid column from said test zone while maintaining said test zone isolated from the major portiony `of said yfluid column,

-' therebydoweringv the pressure in said test zone sufllciently .to initiate iiow of 'formation fluids thereinto without lowering the pressure of said fluid column against the bore hole walls outside of the test zone: and recording changes in fluid character continuously and simultaneously at a plurality of spaced points in said test z'one over a period suillcient for formation fluids to subsaid responsive means through a test period following `opening of said valve.

17. An apparatus as set forth in claim 16 in which said recording means is adapted to start automatically when said valve is opened.

18. Anapparatus as set forth in claim 16 in' which operation of said recording means is initiated by opening of said valve and thereafter continues independently of valve operation.

stantially completely 'displace conditioningiluid in said test zone. i

23. A method of employing automatic recording means responsive to changes in fluid-chan acter for the purpose of determining the relative character and pointsof ingress of formation fluids associated with a bore hole, including the steps ofzloading the bore hole with a fluid distinct in character with respeetto-said formation fluids at sumcient pressure to hold now of the formation fluids in abeyance; lowering a plurality of said automatic recording means into the bore hole to respond to changes in f'iuid character simultaneously at a plurality of 'fixed vertii9. an apparatus asset forth in eiehn 1c in" which said responsive means are in electrical communication with said recording means. and in which said recording means produces a photographic record of the responses to changes in fluid characterin said test zone.

20. `An apparatus for determining the points 'of ingress of formation fluids in a well bore hole, comprising: a tubing string adapted toV extend into a test zone of a bore hole: valve means to control upward flow through said tubing string, said valve means being normally closed and being' adapted to be opened 'when'said tubing is installed in a borehole; a. plurality of means re- Y sponsive to changes in fluid character carried by said tubing string at spaced fixed points relative thereto positioned to iie within said test zone be ail'ected by fluids flowing from said 'test cally spaced points in a' test zone of the bore hole continuously for the duration of a test period; and lowering the pressure of said loading fluidto cause initiation of now of the formation fluids early in said test period.

24. a method or determining the relative eheracter and .points of ingress of formation fluids associated with a bore hole, which method comprises, establishing a vvarying condition of fluids in a test zone in said bore hole by now of formation fluids into said bore hole4 and determining changes in said iluid charactersimultane- 1' ously at a plurality of'selected vertically'spaced points in said testsone for a substantial period of time at each of said spaced` points during vsaid `varying condition. 7o-

25, s method of determining the relative eheracter and points ofingress of formation fluids associated with a borehole which method oom-zy prises, establishing afluid pressure-in a test zone in said -bore hole sunici'ently below formation pressure to` provide `for ilow of formation fluids into said testV zone, and determining changes in iluid character simultaneously at a 'plurality of selected vertically spaced points in said zone for a-substantial period of time at each of said spaced points during said flow of said formation` .sur`e, and determining changes in uid character simultaneously at a plurality of selected vertically spaced points in said zone during said initiation of said iiow.

ananas mining changes in the fluid character at each of ka. plurality of selected vertically spaced fixed -sive with said test period.

g 1 1 `2'7. 'Ihe method ofv determining the relative character and points of ingress of formation iluidsassociated with a bore hole, which method comprises,l establishing a varying condition of fluids in atest zone in said bore hole by iiow of formation iluids into said-bore hole. .and deterpointsA during a test period of substantlallength of time under said varying condition, the determination of said changes in iluid character at each of said points being substantially coexten- JHNI R. lGILLBERGH. 

